Ceramic arc tubes with reduced surface scatter and related methods

• US 20070132153A1
• Filed: 12/13/2005
• Published: 06/14/2007
• Est. Priority Date: 12/13/2005
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Vaidhyanathan, Balasubramaniam, Ramasesha, Sheela, Nayak, Preethi, Aiyer, Hemantkumar, Chandrasekhar, Bukkinakere
• Application Number:
  US11/302,545
• Publication Number:
  US 20070132153A1
• Time in Patent Office: Days
• US Class Current: 264/430
• CPC Class Codes: B24B 1/005 using a magnetic polishing agent
• CPC Class Codes: B24B 1/04 subjecting the grinding or polishing tools, the abrading or polishing medium or work to vibration, e.g. grinding with ultrasonic frequency polishing or abrading surfaces on work by means of tumbling apparatus B24B31/00, involving oscillating or vibrating containers B24B31/06; superfinishing surfaces on work, e.g. by means of abrading blocks reciprocating with high frequency, B24B35/00
• CPC Class Codes: B24B 19/008 for grinding ceramics, pottery, table ware
• CPC Class Codes: B24B 37/00 Lapping machines or devices; Accessories B24B3/00 takes precedence

Abstract

A method for polishing of a ceramic arc tube for use in a HID lamp in order to decrease surface scatter and increase in-line transmission of light through the arc tube. In accordance with one embodiment of the invention, processes are described by which both the inner surface and outer surface of a ceramic arc tube may be polished concurrently. In one embodiment, the ceramic arc tube may be immersed in an abrasive slurry and impacted with the abrasive slurry through generation of a turbulence in the abrasive slurry, for example. In one embodiment, the turbulence may be generated by ultrasonic cavitation within the slurry or by a magnetically induced rotational flow within the slurry.

Claims

1. A method comprising:

polishing concurrently an inner surface and an outer surface of a ceramic arc tube to decrease surface scatter of the arc tube and increase in-line light transmission through the ceramic arc tube.

2. The method of claim 1, wherein the ceramic arc tube is a non-planar ceramic arc tube.

3. The method of claim 2, wherein the non-planar ceramic arc tube comprises an Ra surface roughness of less than 100.

4. The method of claim 2, wherein the non-planar ceramic arc tube comprises an Ra surface roughness of less than 50.

5. The method of claim 1, wherein polishing further comprises:

immersing the ceramic arc tube in an abrasive slurry; and

impacting the ceramic arc tube with particles suspended in the abrasive slurry.

6. The method of claim 5, further comprising generating a turbulence within the abrasive slurry to facilitate said impacting.

7. The method of claim 6, further comprising generating ultrasonic cavitation within the abrasive slurry to facilitate said impacting.

8. The method of claim 1, wherein polishing a ceramic arc tube comprises polishing a material selected from the group consisting of single crystal ceramics, polycrystalline ceramics, and combinations thereof.

9. The method of claim 8, wherein the polycrystalline ceramics comprise one or more ceramics selected from the group consisting of Y₃Al₅O₁₂, Al₂O₃ and combinations thereof.

10. The method of claim 8, wherein the polycrystalline ceramics comprise one or more ceramics selected from the group consisting of Y₂O₃, AlON, Mg₂Al₂O₄, Lu₂O₃ and combinations thereof.

11. A method of polishing a ceramic arc tube comprising:

immersing the arc tube in a slurry comprising suspended abrasive particles; and

generating a turbulence within the slurry such that the abrasive particles are impacted against the inner surface and outer surface of the ceramic arc tube responsive to the turbulence.

12. The method of claim 11, wherein generating a turbulence within the slurry comprises generating ultrasonic cavitation within the slurry such that the abrasive particles are impacted against the inner surface and outer surface of the ceramic arc tube concurrently.

13. The method of claim 12, wherein the abrasive particles comprises diamond particles.

14. The method of claim 13, wherein the diamond particles range in size from about 0.1 μ

m to about 20 μ

m.

15. The method of claim 14, wherein the slurry further comprises a dispersant.

16. The method of claim 12, wherein the ceramic arc tube comprises a material selected from the group consisting of Y₃Al₅O₁₂, Al₂O₃, Y₂O₃, AlON, MgAl₂O₄, Lu₂O₃ and combinations thereof.

17. The method of claim 11, wherein the slurry further comprises magnetic particles suspended in the slurry.

18. The method of claim 17, wherein generating a turbulence within the slurry comprises magnetically inducing a rotational flow within the slurry such that the inner surface and outer surface of the ceramic arc tube are impacted by the abrasive particles concurrently.

19. The method of claim 18, wherein the abrasive particles comprises diamond particles.

20. The method of claim 19, wherein the diamond particles range in size from about 0.1 μ

m to about 20 μ

m.

21. The method of claim 19, wherein the slurry further comprises a dispersant.

22. The method of claim 21, wherein the slurry comprises a viscosity between about 0.5 and 5 centipoises.

23. The method of claim 18, wherein the magnetic particles suspended in the slurry comprise zinc iron ferrite.

24. The method of claim 23, wherein the ceramic arc tube comprises a material selected from the group consisting of Y₃Al₅O₁₂, Al₂O₃, Y₂O₃, AlON, MgAl₂O₄, Lu₂O₃ and combinations thereof.

25. The method of claim 11, wherein the ceramic arc tube comprises a material selected from the group consisting of Y₃Al₅O₁₂, Al₂O₃, Y₂O₃, AlON, MgAl₂O₄, Lu₂O₃ and combinations thereof.